The electric energy meter is a meter used to calculate the electricity consumption. Its unit is "KW·h" (kilowatt hour), which is the "degree" of how much electricity we often say. The normal power of 1kW electrical equipment works The electricity consumed for 1h is 1KW·h (kilowatt·hour), which means 1 kilowatt-hour of electricity is used.
Common electric energy meters are divided into single-phase energy meters, three-phase four-wire active energy meters, three-phase three-wire active energy meters and reactive energy meters. There are two types of electric energy meters currently in use on the market: mechanical and electronic.
Mechanical electric energy meters have the advantages of high overload and low price, but are easily affected by temperature, voltage, frequency and other factors; electronic electric energy meters use integrated circuits to process the collected electrical pulse signals, which have high accuracy, good linearity, and work. Advantages such as wide voltage.
Therefore, electronic watt-hour meters are gradually replacing mechanical watt-hour meters. In the future, electronic watt-hour meters should be preferred when choosing watt-hour meters.
Single-phase meter appearance and technical parameters
The appearance of the electric energy meter has parameters such as rated voltage, rated current, calibration current (rated maximum current), power frequency, accuracy level, and energy meter constant.
Electric energy meter appearance and technical parameters
For example, the nameplate of a single-phase electric energy meter is marked with the following parameters: 220V, 5(20)A, 50Hz, 3200imp/KW·h, which means that the working power supply voltage of this meter is 220V and the rated current is 5A (rated maximum current 20A) , The power frequency is 50Hz, and the electric pulse indicator flashes 3200 times for each degree of rated voltage.
5 (20) A current The current value "5" before the brackets is called the calibration current, which is used to calculate the base current value of the load. The smaller the calibration current, the smaller the starting current of the meter, and the more sensitive the meter. The starting current of the meter is 0.5% of the calibration current. If the calibration current is a 5A meter, the current in the circuit will start counting as long as it is higher than 0.025A, and the meter will not count below this value. The current "20" in brackets is called the rated maximum current, which refers to the maximum current allowed by the electric energy meter to work within the error range for a long time. The electric energy meter can work within the rated maximum current, but it should not exceed this current for long-term use.
The pulse constant of the electric energy meter is 3200imp/KW·h. The pulse indicator of the electric energy meter will flash when the electricity is used. When the pulse indicator flashes 3200 times, the unit digit value of the counter will increase by one, indicating that 1KW·h (degree) has been used. Electricity.
Sometimes if you see the meter at home flashing quickly, it means that the current consumption is relatively large. When the pulse indicator is still flashing when there is no equipment in the home, you need to check whether the electricity has been stolen.
Single-phase meter wiring method
Single-phase electric meters are also divided into straight-through and mutual-inductance types. Generally, single-phase electric meters or straight-through meters are very common. For example, our daily household electricity meters are all straight-through single-phase meters, and there are special cases where the current exceeds the electric energy meter. The measurement range requires the purchase of a transformer-type electric energy meter.
So how to wire the single-phase meter? In fact, there are wiring diagrams on the cover of each electric meter (especially the wiring diagram of the transformer type electric energy meter).
Connection one: direct connection
(1) Line 1 goes in, and line 2 goes out.
(2) Line 3 goes in, and line 4 goes out.
Connection method 2: Transformer type wiring
(1) No. 1 and No. 2 ports are connected to K1 and K2 of the transformer.
(2) Line 3 is connected to the line, and Line 4 is connected to the neutral line.
The choice of the electric energy meter capacity is neither the larger the better, nor the smaller the better, it should match the power consumption. Choosing too large or too small capacity will cause inaccurate measurement, especially when the capacity of the electric energy meter is small, the electric energy meter is easy to burn. Therefore, the current capacity should be calculated for the maximum current of all electrical appliances combined, and it is recommended to use a watt-hour meter with a larger capacity.